Thermostat and alarm circuit controlled thereby.



No. 655,057. Patented July 3|, I900.

. H. G. CARLETON.

THERMCSTAT AND ALARM CIRCUIT CONTROLLED THEREBY.

(Application filed Sept. 8, 1899.)

(No Modem INVE NTUH WITNESSES A TTOHNEKF m: norms PEFER 00., Puoruuwu. WASHINGTON. n. c.

No. 655.057. Patented .Iuly 3|, I900. H. s. CARLETUN.

THERMOSTAT AND ALARM CIRCUIT CONTROLLED THEBEBY.

(Application filed. Sept..8, 1899.)

3 Sheets-Sheet 2.

(No Modul g ,y I 7ZU6IZ757.

' @MZWMW ,me-wcnms wzrzns 00.. momumm WASHINGTON. a, c,

No. 655,057. Patented July 3|, I900.

H. a. CARLETON.

THERMOSTAT AND ALARM CIRCUIT GONTRbLLED THEREBY.

(Application filed Sept. 8; 1899.)

3 Sheets-Sheet 3,

(No Model.)

III-III, 'VIIIIIIIMI THE Nouns PETERS cow, mofliumon vinsumsmu. D. c,

New sm- ATENT' rrrc.

HENRY our CARLETON, on NEW YORK, N. Y., ASSIGNOR TO THE CARLETON ELECTRIC COMPANY, OF SAME PLACE.

THERMOSTAT AND ALARM C I RCUITCONTROLLED THEREBY.

srncrrroerxon forming ea of Letters Patent No. 655,057, dated July 31, ieoo'.

Application filed September 8, 1899. Serial No. 729,796. (No model.)

To all whom it ma mean.-

Be it known that I, HENRY GUY CARLETON, a citizen of the United States, residing at Mam. hatt-an borough, city and county of New York, State of New York, have invented certainnew vide a thermostat which will be reliable, certain, and instantaneous in its operationon a sudden thermal change, which will be equally effective without adjustment throughout a wide range of temperature, such as that occurring during a day or other period of time or between seasons, and which also will be unaifected by normal changes in temperature taking place gradually, so as to avoid operation of the thermostat at undesired times.

The thermostat of the present invention is adapted to be operated by a sudden thermal change in either directionas, for example, a sudden rise in temperature due to the breaking out of a fire or a sudden fall in temperature due to the approach toward each other of a ship and iceberg.

It is also the object of the present invention to construct the thermostat in such way as to adapt it not only for operation upon a sudden thermal change, but for operation upon a gradual rise in temperature above normal conditions, such as might be produced by a smoldering fire.

The invention alsorelates to improvements in fire-alarm circuits controlled by thermostats such asabove referred to. It also relates to certain details in the construction of the thermostat and in the arrangement of electric terminals therefor.- 1

In the accompanying drawings, Figure 1 is a sectional elevationof a thermostat embodying the present invention in its preferred form. Fig. 2 is a diagrammatic View illustrating a series ofsuch thermostats in a nor- Fig. 4 is a diagrammatic View illustrating a series of such thermostats in a normally-open electric fire-alarm circuit. Figs. 5 to 7 are sectional elevations of other modified forms of thermostats embodying the present invention, which will behereinafter described in detail; and Fig. 8 is a sectional elevation of a thermostat embodying the present invention designed for operation on a sudden fall of temperature instead of a sudden rise of tem perature.

The thermostats of the several figures difier from each other in certain particulars, but they each include two coacting hermeticallyclosed chambers or bulbs of unequal thermal sensitiveness containing a gaseous substance and so connected that the pressures therein will be opposed, so that during gradual or normal changes in temperature both bulbs or chambers are affected thereby substantially to the same extent and the opposing pressures in both maintained substantially equal, but on a sudden and substantial thermal change the bulb or chamber of greater sensitiveness is first affected, so as tocause a difference in the relative pressures in the two bulbs or chambers and a corresponding movement relatively to the terminals of the circuit in which the thermostat is located of a displaceable circuit-closer carried by or connected to the thermostat. The term circuit-terminals is used herein in its ordinary sense namely, as indicating terminals leading from a' source of electric energy, as, for example, a battery to the circuit-closer-and not as indieating the electrodes or elements of the source of electric energy depended upon for the work to be done, and the term circuit-closer also is used herein in its ordinary sensenamely, as indicating means capable of closing the circuit between two such terminals. The circuit-closer of the present case preferably will be located in the interior of the thermostat, so as to be displaced directly by the excess of pressure in one bulb or chamber over that in the other but it may be connected to the thermostat in such way as to be dis placed on a rocking or other bodily movement mally-closed electric fire-alarmcircuit. Fig. 3 is a sectional elevation of another form of thermostat embodying the present invention.

the drawings.

be employed in the chambers or bulbs. It may bea permanently-gaseous substance or be formed by the volatilization of volatile sub- It isalso immaterial to thepresent invention, broadly considered, what the character of .the f displaceable circuit-closer carried by or connected to the thermostat may be; but it will preferably be fluid, and the fluid which I pre-- fer is mercury, though other fluidsas sulfuric acid or a solution of mineral salts, &c. may be employed. Where-however, mercury is employed as the circuit-closer and it is located in the thermostat so as to contact with the. gaseous substance in the bulbs or chambers,l.prefer.thatthe gaseous substance employed in the chambers or bulbs should be carbon dioxid, which will not oxidize the mercury. It willbe understood, therefore, that-any suitable gaseous substance and any suitable circuit-closing means carried by or connected to the thermostat may be employed without departing from the invention,broadly considered, in place of those referred to in the detailed description, which will now be given, of the various forms of thermostats illustrated in thedrawings.

,Referrin g now to Figs. 1 and 2, the thermostat and electric'fire-alarm apparatus illus trated therein will first be described. The

thermostat shown in Fig. 1 consists of a pair of-hermetically-closed chambers or bulbs 1 2, of glass or. other suitable material, containing a gaseous substance and'communicating-with eachnother. through a contracted passage-or tube 3 of like material, containing a fluid circuit-closer, as mercury, and having terminals 4 J5 .foranelectric circuit, which enter the tube, through hermetically-sealed openings,

inposition tocontact with the mercury in said tube, theseterminal's'4 5 beingpreferablyof somemetal which, like platinum, is not easily,

amalgamable. The circuit in which the thermostat of 'Fig. 1 is designed to be used is a normally-closed circuit, and the terminals 4 5 therefore enter the tube 3 in such position asto. be nor-mallyin contact with the mercury or other conductivefluid therein, as, i1lus-,

With a slight change in the tratedinV-Fig. 1. positionof the terminals, or one of them, the thermostat wouldbe applicable to anormallyopen circuit, as illustrated in other figures of If both of thebulbs 1 2 of the thermostat of Fig 1 were of equal sensitive ness to thermallchan'ges, they would of course be equally and simultaneously affected by any sudden and substantial change in tempera- 1 ture, such as that produced on the sudden rium, as the pressure in both bulbs wo-uldof course be equal, or substantially so. 'Inthe present case, however, the bulbs 1 2 are of cury or other fluid inthe tube 3 is driven by i the excess of pressure in bulbr2 toward the bulb 1 and out of contact with terminal 4, thus breaking the circuit in which the thermostat is located, while during normal or gradual changes in temperature the pressures in the two bulbs coact to maintain the mercury or other fluid in equilibrium or in contact withboth circuit-terminals 4 5. This inequality in sensitiveness between the bulbs 1 2 is obtained by making the walls of bulb -1 of greater-thickness than the walls-of bulb 2, the diflerence in thicknessof the two bulbs depending upon the difierence required in sensitiveness between the two bulbs. The more sensitive bulb 2 should be as thin as possible in order that it may beiinstautaneously responsive to sudden thermal changes,andthe difference between the two bulbs in thermal sensitiveness should besuchthatthe thermostat will notrespon d to gradual or normal thermal changes, but onlyto suddenor unusual and substantial thermalchanges, such as produced by the sudden breaking out of a fire. The circuit in which the thermostat is located may be of any character and may include any suitable source of electric. energy, as-a battery outsidethe-thermostat, and any form of mechanism-for giving an" alarm audiblyor otherwise or foriperforming any other desired function. The circuit and alarm mechanism, however, which I prefer for some purposes is that illustrated in Fig. 2, including aplurality-of thermostats,each connected with a main circuit '7 8, including a battery 9 and drop-relay magnet 10, controlling, through its armature 11, abranch circuit, including abell 12, andconsisting of wires .13' 14, connected and the pressure-thereincaused to exceed It-hat in the thicker bulb 1, with the result that :the fluidinthe tube 3 is driven by the pressure in bulb 2 toward the bulb 1 and out of contact with the terminal 4, thus breaking thecircuits7 8 and denergizing. magnet .10, the armature 11 of which-is then released and fallsto its rearward position-againstastop 16, aided,; preferably, by-a spring 17. Upon the armature. 11 ismounted a hermetically- :sealed and preferably-exhaustedtube 18, con taining a drop of mercury and terminals leadin-gfrom wires 14 15 of the bell-circuit.

it the forward position of the armature 11 against the magnet the tube 18 is tilted,

so that the drop of mercury therein rests at the end of the tube opposite that occupied by the terminals of wires 14 15; but when said armature is released and falls against stop 16 the tube 18 will be inclined in the opposite direction and the drop of mercury circuit including a drop-relay controlling the' alarm mechanism, yet such closed circuit and such drop-relay are preferred, because with a closed circuit it is impossible for the connections to get out of order without immediate detection,and the thermostats therein may be each readily tested daily, and, furthermore, with a drop-relay immediately upon the operation of a thermostat the bell-circuit is rendered independent of such thermostat and continuous ringing of the bell thus secured regardless of the destruction of such thermostat.

In the case of a smoldering fire it is possible that there might be no sudden rise of temperature sufficient to operate the thermostat in the manner described, the rise being so gradual as to equally and simultaneously affect both the bulbs 1 2, the pressures in which would then maintain the fluid in tube 3 in contact with both of the terminals 4 5. It is desirable to provide for this contingency, and for this reason the bulb 1 of Figs. 1 and 2 is provided at its upper end with a very fragile portion consisting of afinely-drawn-out tubular stem 19, communicating with the interior of said bulb and the outer end of which is adapted to be engaged and broken, so as to release the contents of the bulb 1 by any suitable meansas, for example, a weight, as 20, secured by a fusible connection with the ceiling or other part of the building in which the thermostat may be located. In the present case the means whereby the weight 20 is held in position to engage the stem 19 and by which itis suspended from the ceiling or other part of the room or building consists of a Wire 21, connected with the weight and provided at its upper end with a loop 22, embracing the stem 19 and connected by a fusible wire 23, (fusible, say, at 130,) attached to a hook 24, secured to the ceiling or other part of the room or building. From this construction it results that in case of a smoldering fire, when the'temperature about the thermostat reaches, say, 130, or any other fixed point above normal conditions, the wire 23 will be fused, thus releasing the wire 21 and its weight g 20, with the result that as the latter descend they will exert upon the stem 19 a strain sufficient to break the latter. As the stem- 19 is thus broken the bulb 1 is opened to the at mosphere and the pressure therein reduced below that in the bulb 2, so that the latter will force the fluid in the tube 3, as before described, toward the bulb 1 and out of contact with the terminal 4, thus breaking the main circuit 7 S and closing the bell-circuit. The connection between the weight 20 and the stem 19 will preferably be a loose connection, so that when the weight is released by the fusing of the wire 23 it will acquire a certain amount of momentum before it comes in contact with the stem 19, so as to insure breakage of the latter. For this reason the loop 20 is elongated, and when in position about the stem 19 the upper end of said loop will be out of contact with'said stem, as illustrated in Fig. 1.

As the movement of the fluid in tube 3 is resisted by the pressure in the bulb 1, the latter, in order to reduce such resistance so as to secure free and rapid movement of the fluid, is made larger than the bulb 2 and preferably about three times the size of the latter.

The thermostat of Fig. 3 difiers fromthat of Fig. 1 in the shape and arrangement of tube 3 relatively to the bulbs land 2 and in the arrangement of the terminals 4 5, the thermostat of this figure being designed for use in a normally-open circuit, and the terminal 5 therefore being normally out of contact with the fluid in tube 3. It also differs from the thermostat in Fig. 1 in the omission of the stem 19, though, if desired, the thermostat of Fig. 3, as well as the thermostats of the other figures of the drawings, might obviously, if desired, be equipped with such stems.

In the diagrammatic View, Fig. 4, is illustrated a series of thermostats such as illustrated in Fig. 3 in combination with circuit of the several thermostats a b c are connected by wires a b 0 respectively, and wire 25 to wire 7, leading from one pole of battery 9, and the lower terminals 4 of said thermostats are connected by wires a b 0 which include the annunciators a U0, respectively, to wire 8, including drop-relay magnet 10 and leading to the opposite pole of said battery. The lower terminals 4 of thermostats d e f are connected by wires d e f respectively, to wire 7, while the upper terminals 5 of said thermostats are connected by wires 01 e f including annunciators d e f, to wire 8.

The circuit of this figure is a normally-open one, sothat normally'thearmaturell of magnet 10. is init-s rearward position, and inthis position by means ofa catch;26.retainsa le-g ver 27 in elevated position, said lever carrying a-tube18, containing a drop of mercur This bell-circuit-f consistsof wire7 from one pole of battery 9, wires 28 29,.the terminal of .whicli'latter enters tube 18, wire30, the terminal of which also enters said tube, and Wire 8, leading to" the opposite polejof battery 9. As the construction and operation of the several thermostats is the same',a description of theioperaj-f -tionTof onewill suftlce for an un'derstanding' Selecting, therefore, the thermostat (2,, upon a sudden rise of temperature to a. substantial extent the fluid in thetu'be 3 will bedriven by the excessof pressure in bulb 2 toward bulb 1 and into contact'withthe tor-- minal 5," thus c1osing the circuit through; wires 1 7, battery 9, wire 8, includingfmag-g net ;10, and wire (1 including annunciator'df With the circuit thusclosed magnet 110 is energized and attractsitsarmature 11, which Y then releases thelever 27. As the lever271isf thusreleasd it falls into engagement (aided, if 'desired', bya spring 31.) with. a stop 17 an'd thereby tilts tube 18, the mercury wherein. thencontact's with the terminals of wires '29. 30, and thus closes the bell-circuit and" rings the bell12'. The bell-circuit will remain, th us closed, continuously ringing the alarm, regardl'ess of thedes tru'ct-ion of the thermestatz for closing the bell-circuit.

of all.

mostat, so as to displace fluid circuit-closing means connected to andcarrie'd by the thermostat, which will/presently be described. The'therniost'at of this figureco'nsists of bulbs 1 12, connected by a tube3, which is. pivotally mounted at 35, so as tOfrOckinItOlahd out-of contact with. stops 36 .37; As the fluid in tube '3'.forn1s no part of thecircuit,lany jsuitable non-conducting substance or fluid may be employed in place ,of'mercuryor the like. Normally the thermostat of this figure occiipiesthe position in which it isshownnamely, resting against the stop 37{.'and no change in this "position [will result from .a gradual'ris'e in temperature. Uponasudden use in temperature, however, the bulb 2,1as before, will be afiecte'd thereby and the fluid within the tube 3 be driven by the excess of pressure within'psaid .bulb intothe bulb 1. When the fluidhas'thus been driven into the bulb 1', there will be a' preponderance of weight atlthat endof thetube3, which will cause the tube 3 to rock on its pivot and fall against the stop 36a'nd out'of engagement with the stop 37. Mounted upon the tube 3 is a hermetically-sealed a'ndlexhausted tube 18 provided 'at one end withterminals A 5 and witha drcpof mercury'cons'tituting the icircuit} closer for said'lterminals, and which'when the tube 3 rests against'the stop Iiesat the endof the tube opposite that occupied by the terminals 4 5. when the tube 3 is rocked into engagement with the containedin said tube. Thestufling-boxi in which the terminal 5 is thus mounted consists Q ofacap 32, adapted tobe screwed on' a cor-J respondingly-threaded neck formedon bulb. 1, .anda packing 33, otlrubber or the like;

i nclosingv the rod 5 I and. adapted to moon, pressed by a projection on, thennder side of; the cap 32 as the latter is screwed intoposi-i tion, and to thus hermeticallyfseal bulb' lat itslupp'e'r end. For-convenience infadj usting' thezterminal 5 the tube 3 may be provided:

differentld'egrees of temperature.

with a scale 34, graduated so as to represent.

Inthe thermostats o'f'Figs." 1 to 5 the-fluid.

containedwithin thetube 3 forms part or the circuit in which the thermostat is located, suchcircuit in one case being normallyclosed and broken by movementof the fluid intubei 3fout ofcontact with one terminal, and in othercases normally open and closed by the movement of said fluid into contact with one' terminal. In the thermostat illustratedin Fig.6, however, the fluid or other material in tube3-forms no partof the circuit and merely. acts to rock and alter the position of the ther-g step 36, the tube lsaw umove therewith a d the, drop [of mercury. therein move into'enigagem'entwith the termi'nals't 5, thus'closing' the circuitin which the thermostat is loi mw V. U

IniFigsvl to 6 the circuit-closer carried by .each of the thermostats" is fluid; In the thermostat! illustratedlin' Fig. 7 it consists 'of a metal plate 38, home by a diaphragm 39,, of rubber or other suitable material, interposed betweenthe two chambers. The terminalj l 'isfconnected'with, plate 38, while the other-termi'nalj 5 enters the thermally-i nsulatedbnlbl in. positionl'toj contact with plate 38 when the diaphragm 39 and said plate are displaced by' mostat'illu'strated in Fig. 8, howeveijisde- ,si'gnedfforjoperation" upon a sndden'fall in temperature, such as that, prcduce'd'by the ,approach toward each otherof an iceberg and ,ship. In this .casethe' gas-bulbs 1 and 2 are of substantially the'same'size, but'of uneqlual ickness, as in the preceding figures". Upon ,asudd'enfall of temperature the bulb 2,] as

in the case of a sudden rise in temperature,

,will be first'lafffectediby'suchl sudden fall and the pressure therein reduced below that in the bulb 1, with the result that the fluid contained within the-tube 3 will be forced by the excess of pressure in bulb 1 toward the bulb 2 and into contact with terminal 4, thus closing the circuit. It will be obvious that by a slight change in the position of terminal 4 the thermostat of this figure could as well be applied to a normally-closed circuit.

It is to be understood that many modifications or changes other than those illustrated and described may be resorted to without departing from the spirit and scope of the invention. The invention therefore, broadly considered, is not to be limited to the constructions shown or described, but is to be regarded as generic in its nature.

It will be understood that the present invention is applicable to uses other than those heretofore referred to.

What I claim is-- 1. In a fire-alarm apparatus the combination of an electric circuit including a source of electric energy and suitable alarm mechanism, a thermostat comprising two hermetically-closed chambers containing a gaseous substance and of unequal thickness, a circuit-closer controlled thereby, and circuit-terminals leading from the source of energy to and controlled by the circuit-closer, substantially as described.

2. In a fire-alarm apparatus the combination of an electric circuit including a source of electric energy and suitable alarm mechanism, a thermostat comprising two hermetically-closed chambers containing a gaseous substance and of unequal thickness, a fluid circuit-closer controlled thereby, and circuitterminals leading from the source of energy to and controlled by the circuit-closer, substantially as described.

8. In a fire-alarm apparatus the combination of an electric circuit includinga source of electric energy and suitable alarm mechanism, a thermostat comprising two hermetically-closed chambers containing a gaseous substance and of unequal thickness, a dis- .placeable circuit-closer between said chambers, and circuit-terminals leading from the source of energy to and controlled by the circuit-closer, substantially as described.

4.. In a fire-alarm apparatus the combination of an electric circuit including a source of electric energy and suitable alarm mechanism, a thermostat comprising two hermetically-closed chambers containing a gaseous substance and of unequal thickness, a fluid circuitcloser between said chambers, and circuit-terminals leading from the source of energy to and controlled by the circuit-closer, substantially as described.

5. In a fire-alarm apparatus the combination of an electric circuit including a source of electric energy and suitable alarm mechanism, a thermostat comprising two hermetically-closed chambers containinga gaseous substance and of unequal thickness, a cire55,o57 n 'cuit-closer of mercury controlled thereby, and circuit-terminals leading from the source of energy to and controlled by the circuit-closer, substantially as described.

6. In a fire-alarm apparatus the combination of an electric circuit including a source of electric energy and suitable alarm mechanism, a thermostat comprising two hermetically-closed chambers containing a gaseous substance and of unequal thickness, acircuitcloser of mercury between said chambers, and circuit-terminals leading from the source of energy to and controlled by the circuitcloser, substantially as described. 7

7 A thermostat comprising two coacting hermetically-closed chambers containing a gaseous substance and of unequal thickness and a circuit-closer controlled thereby, substantially as described.

8. A thermostat comprising two coacting hermetically-closed chambers containing a gaseous substance and of unequal thickness and a tubular connecting portion through which they coact and a circuit-closer controlled thereby, substantially as described.

9. A thermostat comprising two coacting hermetically-closed chambers of unequal thickness, a displaceable circuit-closer between said chambers, and circuit-terminals, controlled by said circuit-closer, for connection with a source of electric energy, substantially as described.

. 10. A thermostat comprising two hermetically-closed chambers of unequal thickness and a tubular connecting portion through which they coact containing a displaceable circuit-closer, and circuitterminals, controlled by said circuit-closer, for connection with a source of electric energy, substantially as described.

11. A thermostat comprising two hermetically-closed chambers of unequal thickness and a tubular connecting portion through which they coact containing a circuit-closer of mercury, and circuit-terminals, controlled by said circuit-closer, for connection with a source of electric energy, substantially as described.

12. A thermostat comprising two coacting hermetically-closed chambers containing a gaseous substance and of unequal thermal sensitiveness, the less-sensitive chamber being of larger size than the other and a circuit-closer controlled thereby, substantially as described.

13. A thermostat comprising two coacting hermetically-closed chambers containing a gaseous substance and of unequal thickness, the chamber of greater thickness being of larger size than the other and a circuit-closer controlled thereby,substantially as described.

14. Athermostat comprising two coacting hermetically-closed chambers, one of said chambers being provided with a portion more fragile than the body thereof, substantially as described.

15. A thermostat comprising two coacting hermetically-closed chambers of unequal thermal sensiti veness, the? less-sen sitive chamber being provided with a portion more fragile than the body thereof, substantiallyas de scribed;

165A thermostat comprising two coacting hermetically-closed chambers, one of said.

being provided with a fragile tubular stem communicating with its interior,substantially of electric energy'and" entering the thermostat in position for contact with saidcircuit- "closer substantially as describedrf In a fire-alarm.apparatus'thecoinbination of a main circuit includin'gadrop-relay, an alarm-circuit controlled bythe latter, a thermostat in the main circuit comprising two coacting hermetically-closed chambers containing a gaseous substance and of, unequal thermal sensitiveness,the less-sensitive cham- "ber being provided with a portionmorefragile :than the body thereof, a device for, engaging and breaking said fragile portion-,ifu'sible means for supporting saiddeviceout .of

breaking position, and a' circuit-cl'oser'conas described.

18."A thermostat comprising two coacting hermetically closed chambers of unequal thickness, the thicker .chamber being prodescribed.

26. In a fire-alarmapparatus th'e-combinar tion of a main circuit including a drop-relay,

trolled by the thermostat, substantially as vided with a portionmore fragile than the bodythereof, substantiallyfas described.

19; A thermostat comprising two coacting hermetically closed chambers of unequal thickness,--the thicker chamber being provided witha fragile tubular stem comm'uni eating with'its interior, substantially as described; V

20. 1A thermostat comprising bulbs 1, 2,

connected so as to coact, bulb 1 being provided with fragile tubular stem 19, substantiallyfas described.

l 21. Athermostat comprising bulbs 1, 2,and connecting-tube 3, bulb 1 being provided with fragile tubular stem 19, substantially as described t 22. Ina fire-alarm apparatus the combination of a main circuit including a source of electric energy and a drop-relay, an alarmcircuit controlled by the latter, a thermostat in the main circuit comprising two coacting hermetically-closed chambers containing a gaseous substance and of unequal thickness, I

"a circuit-closer controlled by the thermostat, andcircuit-terminals leading from the source of electric energyto and controlled by the circuit-closer, substantially as described.

23.'*In a fire-alarm apparatus the combination of a main circuit including a source of electricenergy and a drop-relay, an alarmcircuit controlled bythe latter, a thermostat infthe'rnain circuit comprising two coacting hermetically-closed chambers containing a gaseoussubstance and of unequal thickness,

acircuit-closer between. the chambers, and. circuit-terminals leading from the source of? electric energy and entering the thermostat inposition forlcontact with said circuit-closer substantially as described.

24:1119. fire-alarm apparatus the combina tion 'ofa main circuit including a source of electric. energy and a drop-relay, an alarmcircuitfcontrolled by the latter, a thermostat in the main circuit comprising twocoacting hermetically-closed chambers containing a gaseous-substance and of unequal thickness,

a fluid circuit closer between the chambers,-1 and circuit-terminalsleading from the source an alarm-circuit controlled by the latter, a thermostat in the main'circu-itcomprising two coacting hermetically-closed chambers containing a gaseous substance and of unequal thermal sensitiveness,the less-sensitive chamber being] provided with a fragile tubular stem communicating with its interior, a-device for engaging and breaking said. stem, fusible'means for supporting said'device out of breaking position, and a circuit-closer con;

trolled by the thermostat, substantially as tween the chambers,- and circuit-terminals entering the thermostat in position forcontact with said circuit-closer, substantially "as described. i'

i 28; In a fire-alarm apparatus the combina tion of a main circuit including a drop-relay,

thermalsensitiveness,thelessesensitivechamr ber being provided witha fragile, tubular stem communicating with its interior, a devicefor engaging and breaking said'stem, fusible means for supporting said device out of breakingposition, a fluid circuit-"closer be tion of a main circuit including .a source of 1 electric'energy and a drop-relay,.an alarmcirc'uit controlled by the'latter, 'a thermostat I .analarm-circuit controlled by the latter,..a thermostat in the main circuit comprising two .coacting hermetically-closed chambers containing a gaseous substanceand of unequalfrzo in the main circuit comprising bulbs 1, 2, containing a gaseous substance and of unequal thickness, and tube 3 connecting said chambers and provided with a circuit-closing fluid and terminals 4, 5, leading from the source of electric energy and adapted to contact with said fluid, substantially as described.

30. In a fire-alarm apparatus the combination of a main circuit including a drop-relay, an alarm-circuit controlled by the latter, a thermostat in the main circuit comprising bulbs 1, 2, containing a gaseous substance and tube 3 connecting said chambers and provided with a circuit-closing fluid and terminals 4, 5, adapted to contact with said fluid, the bulb 1 being provided with fragile tubular stem 19, substantially as described.

31. In a fire-alarm apparatus the combination of a main circuit including a drop-relay, an alarm-circuit controlled by the latter, a thermostat. in the main circuit comprising bulbs 1, 2, containing a gaseous substance and tube 3 connecting said chambers and provided with a circuit-closing fluid and terminals 4, 5, adapted to contact with said fluid, the bulb 1 being provided with fragile tubular stem 19, a weight 20 for engaging and breaking said sten1,and fusible means for supportingsaid weight out of breaking position, substantially as described.

32. In a fire-alarm apparatus the combination of a main circuit including a source of electric energy and a drop-relay, an alarmcircuit controlled by the latter, a series of thermostats in the main circuit,each comprising two ooacting hermetically-closed chambers containing a gaseous substance and of unequal thickness, a circuit-closer and an annunciator for each thermostat, and circuitterminals leading from the source of electric energy to and controlled by the circuit-closer substantially as described.

33. In a fire-alarm apparatus the combination of amain circuit including a source of electric energy and a drop-relay, an alarmcircuit controlled by the latter, a series of thermostats in the main circuit, each comprising two coacting hermeticallyclosed chambers containing a gaseous substance and of unequal thickness, a circuit-closer between the chambers, and circuit-terminals leading from the source of electric energy and entering the thermostat in position for contact with said circuit-closer, and an annunciator for each thermostat substantially as described."

34. In a fire-alarm apparatus the combination of a main circuit including a source of electric energy and a drop-relay, an alarmcircuit controlled by the latter, a series of thermostats in the main circuit, each comprising two coacting hermetically-closed chambers containing a gaseous substance and of unequal thickness, a fluid circuit-closer be tween the chambers, and circuit terminals leading from the source of electric energy and entering the thermostat in position for contact with said circuit-closer, and an annunciator for each thermostat substantially as described. I

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

HENRY GUY OARLETON.

Witnesses:

T. F. KEHOE, G. M. BORST. 

